Catalyst recovery in hydrothermal treatment of biomass

ABSTRACT

Biomass based feeds are processed under hydrothermal treatment conditions to produce a hydrocarbon liquid product and a solids portion. The hydrothermal treatment is performed in the presence of catalyst particles. The presence of the heterogeneous catalyst can modify the nature of the hydrocarbon products produced from the hydrothermal treatment. After the hydrothermal treatment, the catalyst particles can be separated from the algae-based solids, to allow for recycle of the catalyst particles.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application relates to and claims priority to U.S. ProvisionalPatent Application No. 61/422,438 of the same title filed Dec. 13, 2010.

This application is also related to the following co-pending, commonlyassigned, applications: (1) U.S. patent application Ser. No. ______(Attorney Docket No. 2010EM355-US) entitled “Hydrothermal Treatment ofBiomass with Heterogeneous Catalyst” filed ______ 2011 which claimspriority to U.S. Provisional Patent Application No. 61/422,400 of thesame title filed Dec. 13, 2010; (2) U.S. patent application Ser. No.______ (Attorney Docket No. 2010EM356-US) entitled “Phosphorous Recoveryfrom Hydrothermal Treatment of Biomass” filed ______ 2011 which claimspriority to U.S. Provisional Patent Application No. 61/422,455 of thesame title filed Dec. 13, 2010; and (3) U.S. patent application Ser. No.______ (Attorney Docket No. 2010EM358-US) entitled “CatalyticHydrothermal Treatment of Biomass” filed ______ 2011 which claimspriority to U.S. Provisional Patent Application No. 61/422,427 of thesame title filed Dec. 13, 2010.

The contents of each of the above applications are hereby incorporatedby reference in their entirety.

FIELD OF THE INVENTION

This invention relates to hydrothermal treatment of various types ofbiomass, such as algae, to produce hydrocarbon products, such asdistillate fuel.

BACKGROUND OF THE INVENTION

Conventional production of fuels and lubricants is still dominated byconversion of mineral petroleum feeds into desired products. In order tosupplement and/or replace the conventional sources with renewable formsof energy, a variety of problems must be overcome.

One alternative to conventional fuels and lubricants is to producecomparable fuels and lubricants based on biomass. One advantage ofbiomass based fuels is that the resulting fuel product may be compatiblewith existing infrastructure and technologies. Ideally, biomass basedfuels and lubricants could be used in a “drop-in” fashion in place ofconventional products, allowing the use of a renewable product withouthaving to modify existing equipment.

One option for processing of a biomass type feed is hydrothermalprocessing. Hydrothermal processing involves exposing a feed to waterunder elevated temperature and pressure conditions. U.S. Pat. No.6,180,845 provides an example of this type of process. This patentdescribes a process for transforming biomass to hydrocarbon mixturesusing near-critical or supercritical water. The process can be used on avariety of initial biomass materials. The biomass is processed atpressures from 200 bars (20 MPa) to 500 bars (50 MPa) and attemperatures from 320° C. to 500° C. The atmosphere in the reactor isdescribed as non-oxidizing, and hydrogen is included in an example.About 4 hours is noted as a preferred processing time. The hydrothermalprocessing is described as producing a “petroleum like liquid”, whichappears to include a substantial portion of aromatic and polymericspecies, as well as some soot and/or carbonized residues. Thedescription mentions that some metals present in the biomass feed, suchas Ni or Fe, can alter the types of products generated. The descriptionalso mentions that metals can be used to simplify the components of theproduct mixture, or to remove unwanted compounds. The only metalspecifically mentioned as an additive is Cu metal for removal of sulfurcompounds such as thiophenes. Nitrogen compounds are identified asanother product that can be removed by precipitation with metals,although no examples of a suitable metal are provided. It appears fromthe description that the additive metals used are “reduced metals”, asopposed to metals in an oxidized state.

PCT Publication No. WO 96/30464 provides another example of processingof biomass at supercritical conditions. The application describesprocessing of wet biomass, such as algae or water hyacinth, to producegaseous hydrocarbons and hydrogen. The conversion conditions includecontacting the biomass with water under supercritical conditions, whichis defined as having a temperature of greater than 374° C. and apressure greater than 22.1 MPa. The conversion takes place in thepresence of a carbon based catalyst, such as charcoal or an activatedcarbon with a high surface area. The process is described as providingrapid and virtually complete gasification of organic matter in afeedstock.

SUMMARY OF THE INVENTION

In one aspect of the invention, a method for hydrothermally processingbiomass is provided. The method includes contacting an algae based feedwith water in the presence of catalyst particles under effectivehydrothermal processing conditions to produce a multi-phase product, thecatalyst particles including a catalyst metal and having an averageparticle size of at least about 1000 μm. The multi-phase product can beseparated to produce at least a gas phase portion, a liquid hydrocarbonportion, an aqueous portion, and a solids portion, the solids portioncontaining the catalyst particles and algae based solids. The catalystparticles can also be separated from the algae based solids.

In another aspect of the invention, another method for hydrothermallyprocessing biomass is provided. The method includes contacting an algaebased feed with water in the presence of catalyst particles undereffective hydrothermal processing conditions to produce a multi-phaseproduct, the catalyst particles including a catalyst metal and having aminimum average particle dimension of at least about 1000 μm. Themulti-phase product can be separated to produce at least a gas phaseportion, a liquid hydrocarbon portion, an aqueous portion, and a solidsportion, the solids portion containing the catalyst particles and algaebased solids. The catalyst particles can also be separated from thealgae based solids.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a reaction system suitable for performing a processaccording to an embodiment of the invention.

FIG. 2 schematically shows a reaction scheme according to an embodimentof the invention.

FIG. 3 depicts a reaction system suitable for performing a processaccording to another embodiment of the invention.

FIGS. 4 a and 4 b show distillation profiles for hydrocarbon productsfrom hydrothermal treatment.

FIG. 5 shows particle size profiles for an algae sample before and afterhydrothermal treatment.

DETAILED DESCRIPTION OF THE EMBODIMENTS Overview

In various embodiments, catalytic methods are provided for hydrothermaltreatment of algae feeds (or other biomass based feeds) to producedistillate boiling range products. The hydrothermal treatment caninclude processing of biomass feeds in the presence of water atsupercritical or near-supercritical temperatures and pressures.Hydrothermal treatment of an algae feed in the presence of a catalystcan allow for conversion of biomass into molecules having a desiredboiling range while also removing at least a portion of impurities thatmay be less desirable in a distillate product, such as nitrogenimpurities, oxygen impurities, olefin impurities, aromatic impurities,and the like.

In some embodiments, the catalysts can be selected to facilitateseparation of the catalyst particles from other solids generated fromthe hydrothermal treatment process. For example, the particle size ofthe catalyst can be selected so that the catalyst particles can beseparated from other solids by filtration and/or by other physicalmeans, such as a hydrocyclone. Additionally or alternately, a catalystcan be selected that is resistant to attrition and/or resistant to otherbreakdown mechanisms within a hydrothermal treatment process. This canallow the catalyst particle to maintain the original properties of thecatalyst, such as properties that are beneficial for separating thecatalyst particles from other solids.

One advantage of a catalyst that can be separated from other productsolids can be that the catalyst can allow the use of catalyst materialsthat are less compatible with biomass production processes. For example,one product from hydrothermal treatment of algae or other biomass can bephosphorus. Because phosphorus is a nutrient for growth of algae orother biomass, recycling the phosphorus from a hydrothermal treatmentprocess can be beneficial. Unfortunately, metals such as Co or Mo may beharmful to growth processes for algae and other types of biomass. Ifmetals that are less biocompatible are recycled to growth environmentsfor biomass, the growth rate of desired algae or other biomass can besuppressed. Selecting a catalyst that can be separated with greaterefficiency from other product solids can allow for use of catalystmetals that have lower biocompatibility. The less biocompatible metalscan then be separated out from other product solids by separating outthe catalyst particles. This can allow greater flexibility in choosing adesired catalyst while still allowing for recycle of a portion of theproduct solids as nutrients to an algae growth environment (or otherbiomass growth environment).

Algae can contain significant amounts of products such as triglycerides,fatty acids/alcohols, and isoprenoids, which can be converted tovaluable products such as transportation fuels and lubricants. However,a number of challenges exist in converting an algae feed into a usableproduct. One challenge is recovering the desired hydrocarbon moleculesfrom the algae. An option for recovering hydrocarbon products from algaecan be to use a solvent extraction based method. Unfortunately, somesolvent based methods require use of an algae source that containslittle or no water. Dehydration of an algae source to a sufficientdegree to allow for this type of solvent extraction can require a highcost of operation. Alternative solvent extraction methods can allow forextraction from an algae sample that contains water. However, a highcost step usually remains, as the solvent has to be separated from thewater, for example by distillation.

As an alternative to solvent extraction, hydrothermal processing can beused to extract hydrocarbon products from an algae source. Hydrothermalprocessing has the advantage that it can be performed without vaporizingwater, which can reduce the cost of the process. However, anotherdifficulty with using biomass to produce hydrocarbon products can be thepresence of impurities in the biomass. An algae feed can have arelatively high concentration of molecules that can contain, inter alia,sulfur, nitrogen, oxygen, phosphorus, Group I metals, Group II metals,transition metals, olefinic groups, and aromatic groups. Due to the highimpurity levels, additional processing can be required before thehydrocarbon products from non-catalytic hydrothermal processing can beused in conventional processes.

Feedstocks

In various embodiments of the invention, an algae feed or anotherbiomass based feed can be processed using catalytic hydrothermalprocessing. In one exemplary embodiment, the feed can typically containalgae and water, and optionally can contain additional feed from anotherbiocomponent source, where a biocomponent source is any source includingand/or derived from biological material, such as from plants, animals,microbes, algae, or a combination thereof. In another embodiment, thefeed can be a feed derived from a starting mixture containing algae andwater, and can optionally contain feed from another biocomponent source.In still another embodiment, the feed can generally be a feed based onbiomass.

It is noted that the water present in an algae (or other biomass) feedcan include extracellular water and/or intracellular water.Intracellular water refers to water contained within the cell membraneof a cell, such as an algae cell. For an algae feed, a feed that appearsrelatively dry based on extracellular water content, can still contain asubstantial portion of intracellular water. For algae whose cell wallshave been ruptured (e.g., substantially dried/dewatered algae), thealgae feed can only contain extracellular water (as ruptured cells donot have an inside, but only an outside). For an algae feed thatcontains intracellular water, computing the ratio of water to (dry)algae requires determining what portion of the algae weight is due tointracellular water, as the intracellular water should count toward theweight of water and not the weight of dry algae. As a clarifyingexample, an algae sample could include no extracellular water and stillhave a water to algae ratio of about 1:1 or greater, for example about2:1 or greater, due to the amount of intracellular water in the algae.Thus, references herein to the weight of algae refer to the weight ofdry algae, excluding intracellular water.

For a feed containing at least algae and water, the algae content of thefeed can be at least about 5 wt %, for example at least about 10 wt %,at least about 20 wt %, at least about 25 wt %, or at least about 30 wt%. Additionally or alternately, the algae content of the feed can beabout 50 wt % or less, for example about 30 wt % or less, about 25 wt %or less, or about 20 wt % or less. In terms of ratios, the ratio ofwater to algae in the feed can be at least about 1:1, for example atleast about 2:1, at least about 3:1, or at least about 4:1. Additionallyor alternately, the ratio of water to algae can be about 25:1 or less,for example about 20:1 or less or about 10:1 or less. In someembodiments, the algae content of the feed relative to the amount ofwater can be based on practical considerations regarding extraction ofwater from the source of the algae. Thus, in some embodiments, algae canbe introduced into a reactor as a mixture or paste of algae and water.Additionally or alternately, a dried form of algae can be introducedinto a reactor along with sufficient water, e.g., to reach a desiredratio of algae to water.

Algae oils or lipids can typically be contained in algae in the form ofmembrane components, storage products, and/or metabolites. Certain algalstrains, particularly microalgae such as diatoms and cyanobacteria, cancontain proportionally high levels of lipids. Algal sources for thealgae oils can contain varying amounts, e.g., from 2 wt % to 80 wt % oflipids, based on total weight of the biomass itself.

Algal sources for algae oils can include, but are not limited to,unicellular and multicellular algae. Examples of such algae can includea rhodophyte, chlorophyte, heterokontophyte, tribophyte, glaucophyte,chlorarachniophyte, euglenoid, haptophyte, cryptomonad, dinoflagellum,phytoplankton, and the like, and combinations thereof. In oneembodiment, algae can be of the classes Chlorophyceae and/or Haptophyta.Specific species can include, but are not limited to, Neochlorisoleoabundans, Scenedesmus dimorphus, Euglena gracilis, Phaeodactylumtricornutum, Pleurochrysis carterae, Prymnesium parvum, Nannochloropsisgaditiana, Tetraselmis chui, Tetraselmis tertiolecta, Dunaliella salina,various species of Chlorella, and Chlamydomonas reinhardtii. Nonlimitingexamples of additional or alternate algal sources include one or moremicroalgae of the Achnanthes, Amphiprora, Amphora, Ankistrodesmus,Asteromonas, Boekelovia, Borodinella, Botryococcus, Bracteococcus,Chaetoceros, Carteria, Chlamydomonas, Chlorococcum, Chlorogonium,Chlorella, Chroomonas, Chrysosphaera, Cricosphaera, Crypthecodinium,Cryptomonas, Cyclotella, Dunaliella, Ellipsoidon, Emiliania,Eremosphaera, Ernodesmius, Euglena, Franceia, Fragilaria, Gloeothamnion,Haematococcus, Halocafeteria, Hymenomonas, Isochrysis, Lepocinclis,Micractinium, Monoraphidium, Nannochloris, Nannochloropsis, Navicula,Neochloris, Nephrochloris, Nephroselmis, Nitzschia, Ochromonas,Oedogonium, Oocystis, Ostreococcus, Pavlova, Parachlorella, Pascheria,Phaeodactylum, Phagus, Platymonas, Pleurochrysis, Pleurococcus,Prototheca, Pseudochlorella, Pyramimonas, Pyrobotrys, Scenedesmus,Skeletonema, Spyrogyra, Stichococcus, Tetraselmis, Thalassiosira,Viridiella, and Volvox species, and/or one or more cyanobacteria of theAgmenellum, Anabaena, Anabaenopsis, Anacystis, Aphanizomenon,Arthrospira, Asterocapsa, Borzia, Calothrix, Chamaesiphon,Chlorogloeopsis, Chroococcidiopsis, Chroococcus, Crinalium,Cyanobacterium, Cyanobium, Cyanocystis, Cyanospira, Cyanothece,Cylindrospermopsis, Cylindrospermum, Dactylococcopsis, Dermocarpella,Fischerella, Fremyella, Geitleria, Geitlerinema, Gloeobacter,Gloeocapsa, Gloeothece, Halospirulina, Iyengariella, Leptolyngbya,Limnothrix, Lyngbya, Microcoleus, Microcystis, Myxosarcina, Nodularia,Nostoc, Nostochopsis, Oscillatoria, Phormidium, Planktothrix,Pleurocapsa, Prochlorococcus, Prochloron, Prochlorothrix, Pseudanabaena,Rivularia, Schizothrix, Scytonema, Spirulina, Stanieria, Starria,Stigonema, Symploca, Synechococcus, Synechocystis, Tolypothrix,Trichodesmium, Tychonema, and Xenococcus species.

After catalytic hydrothermal processing, a portion of the products fromcatalytic hydrothermal processing can be combined with biocomponentand/or mineral based feeds. The combined feedstock can include varyingamounts of feedstreams based on biocomponent sources. When desired, thefeed can include at least about 0.1 wt % of feed based on a biocomponentsource, for example at least about 0.5 wt %, at least about 1 wt %, atleast about 3 wt %, at least about 10 wt %, at least about 15 wt %, atleast about 25 wt %, at least about 50 wt %, or at least about 75 wt %.In such embodiments, the feed can additionally or alternately includeabout 100 wt % or less of biocomponent, for example about 90 wt % orless, about 75 wt % or less, or about 50 wt % or less. In otherembodiments, the amount of biocomponent feed (e.g., for co-processingwith the mineral oil portion of the feed) can be relatively small, forinstance with a feed that includes at least about 0.5 wt % of feedstockbased on a biocomponent source, e.g., at least about 1 wt %, at leastabout 2.5 wt %, or at least about 5 wt %, at least about 10 wt %, or atleast about 20 wt %. In such embodiments, the feed can additionally oralternately include about 50 wt % or less of biocomponent basedfeedstock, for example about 25 wt % or less, about 20 wt % or less,about 10 wt % or less, or about 5 wt % or less.

In various embodiments of the invention, the combined feedstock caninclude feeds from various biomass or biocomponent sources, such asvegetable (higher plant), animal, fish, and/or algae. Generally, thesebiocomponent sources can include vegetable fats/oils, animal fats/oils,fish oils, pyrolysis oils, and algae lipids/oils, as well as componentsof such materials, and in some embodiments can specifically include oneor more type of lipid compounds. Lipid compounds are typicallybiological compounds that are insoluble in water, but soluble innonpolar (or fat) solvents. Non-limiting examples of such solventsinclude alcohols, ethers, chloroform, alkyl acetates, benzene, andcombinations thereof.

Major classes of lipids include, but are not necessarily limited to,fatty acids, glycerol-derived lipids (including fats, oils andphospholipids), sphingosine-derived lipids (including ceramides,cerebrosides, gangliosides, and sphingomyelins), steroids and theirderivatives, terpenes and their derivatives, fat-soluble vitamins,certain aromatic compounds, and long-chain alcohols and waxes.

In living organisms, lipids generally serve as the basis for cellmembranes and as a form of fuel storage. Lipids can also be foundconjugated with proteins or carbohydrates, such as in the form oflipoproteins and lipopolysaccharides.

Examples of vegetable oils that can be used in accordance with thisinvention include, but are not limited to rapeseed (canola) oil, soybeanoil, coconut oil, sunflower oil, palm oil, palm kernel oil, peanut oil,linseed oil, tall oil, corn oil, castor oil, jatropha oil, jojoba oil,olive oil, flaxseed oil, camelina oil, safflower oil, babassu oil,tallow oil and rice bran oil.

Vegetable oils as referred to herein can also include processedvegetable oil material. Non-limiting examples of processed vegetable oilmaterial include fatty acids and fatty acid alkyl esters. Alkyl esterstypically include C₁-C₅ alkyl esters. One or more of methyl, ethyl, andpropyl esters are preferred.

Examples of animal fats that can be used in accordance with theinvention include, but are not limited to, beef fat (tallow), hog fat(lard), turkey fat, fish fat/oil, and chicken fat. The animal fats canbe obtained from any suitable source including restaurants and meatproduction facilities.

Animal fats as referred to herein also include processed animal fatmaterial. Non-limiting examples of processed animal fat material includefatty acids and fatty acid alkyl esters. Alkyl esters typically includeC₁-C₅ alkyl esters. One or more of methyl, ethyl, and propyl esters arepreferred.

Other biocomponent feeds usable in the present invention can include anyof those which comprise primarily triglycerides and free fatty acids(FFAs). The triglycerides and FFAs typically contain aliphatichydrocarbon chains in their structure having from 8 to 36 carbons,preferably from 10 to 26 carbons, for example from 14 to 22 carbons.Types of triglycerides can be determined according to their fatty acidconstituents. The fatty acid constituents can be readily determinedusing Gas Chromatography (GC) analysis. This analysis involvesextracting the fat or oil, saponifying (hydrolyzing) the fat or oil,preparing an alkyl (e.g., methyl) ester of the saponified fat or oil,and determining the type of (methyl) ester using GC analysis. In oneembodiment, a majority (i.e., greater than 50%) of the triglyceridepresent in the lipid material can be comprised of C₁₀ to C₂₆ fatty acidconstituents, based on total triglyceride present in the lipid material.Further, a triglyceride is a molecule having a structure identical tothe reaction product of glycerol and three fatty acids. Thus, although atriglyceride is described herein as being comprised of fatty acids, itshould be understood that the fatty acid component does not necessarilycontain a carboxylic acid hydrogen. In one embodiment, a majority oftriglycerides present in the biocomponent feed can preferably becomprised of C₁₂ to C₁₈ fatty acid constituents, based on totaltriglyceride content. Other types of feed that are derived frombiological raw material components can include fatty acid esters, suchas fatty acid alkyl esters (e.g., FAME and/or FAEE).

Biocomponent based diesel boiling range feedstreams can have a widerange of nitrogen and/or sulfur contents. For example, a biocomponentbased feedstream based on a vegetable oil source can contain up to about300 wppm nitrogen. In contrast, a biomass based feedstream containingwhole or ruptured algae can sometimes include a higher nitrogen content.Depending on the type of algae, the nitrogen content of an algae basedfeedstream can be at least about 2 wt %, for example at least about 3 wt%, at least about 5 wt %, or at least about 10 wt %, and algae withstill higher nitrogen contents are known. The sulfur content of abiocomponent feed can also vary. In some embodiments, the sulfur contentcan be about 500 wppm or less, for example about 100 wppm or less, about50 wppm or less, or about 10 wppm or less.

Aside from nitrogen and sulfur, oxygen can be another heteroatomcomponent in biocomponent based feeds. A biocomponent diesel boilingrange feedstream based on a vegetable oil, prior to hydrotreatment, caninclude up to about 10 wt % oxygen, for example up to about 12 wt % orup to about 14 wt %. Additionally or alternately, such a biocomponentdiesel boiling range feedstream can include at least about 1 wt %oxygen, for example at least about 2 wt %, at least about 3 wt %, atleast about 4 wt %, at least about 5 wt %, at least about 6 wt %, or atleast about 8 wt %. Further additionally or alternately, a biocomponentfeedstream, prior to hydrotreatment, can include an olefin content of atleast about 3 wt %, for example at least about 5 wt % or at least about10 wt %.

A mineral hydrocarbon feedstock refers to a conventional (e.g.,non-biocomponent) hydrocarbon feedstock, typically derived from crudeoil and that has optionally been subjected to one or more separationand/or other refining processes. In one preferred embodiment, themineral hydrocarbon feedstock can be a petroleum feedstock boiling inthe diesel range or above. Examples of suitable feedstocks can include,but are not limited to, virgin distillates, hydrotreated virgindistillates, kerosene, diesel boiling range feeds (such as hydrotreateddiesel boiling range feeds), light cycle oils, atmospheric gasoils, andthe like, and combinations thereof.

Mineral feedstreams for blending with a biocomponent feedstream can havea nitrogen content from about 50 wppm to about 2000 wppm nitrogen, forexample from about 50 wppm to about 1500 wppm or from about 75 to about1000 wppm. In some embodiments, the mineral feedstream can have a sulfurcontent from about 100 wppm to about 10,000 wppm sulfur, for examplefrom about 200 wppm to about 5,000 wppm or from about 350 wppm to about2,500 wppm. Additionally or alternately, the combined (biocomponent plusmineral) feedstock can have a sulfur content of at least about 5 wppm,for example at least about 10 wppm, at least about 25 wppm, at leastabout 100 wppm, at least about 500 wppm, or at least about 1000 wppm.Further additionally or alternately, the combined feedstock can have asulfur content of about 2000 wppm or less, for example about 1000 wppmor less, about 500 wppm or less, about 100 wppm or less, or about 50wppm or less. Still further additionally or alternately, the nitrogencontent of the combined feedstock can be about 1000 wppm or less, forexample about 500 wppm or less, about 100 wppm or less, about 50 wppm orless, about 30 wppm or less, about 20 wppm or less, or about 10 wppm orless.

The content of sulfur, nitrogen, oxygen, and olefins in a feedstockcreated by blending two or more feedstocks can typically be determinedusing a weighted average based on the blended feeds. For example, amineral feed and a biocomponent feed can be blended in a ratio of 80 wt% mineral feed and 20 wt % biocomponent feed. If the mineral feed has asulfur content of about 1000 wppm, and the biocomponent feed has asulfur content of about 10 wppm, the resulting blended feed could beexpected to have a sulfur content of about 802 wppm.

Diesel boiling range feedstreams suitable for use in the presentinvention tend to boil within the range of about 215° F. (about 102° C.)to about 800° F. (about 427° C.). Preferably, the diesel boiling rangefeedstream has an initial boiling point of at least about 215° F. (about102° C.), for example at least about 250° F. (about 121° C.), at leastabout 275° F. (about 135° C.), at least about 300° F. (about 149° C.),at least about 325° F. (about 163° C.), at least about 350° F. (about177° C.), at least about 400° F. (about 204° C.), or at least about 451°F. (about 233° C.). Preferably, the diesel boiling range feedstream hasa final boiling point of about 800° F. (about 427° C.) or less, or about775° F. (about 413° C.) or less, or about 750° F. (about 399° C.) orless. In some embodiments, the diesel boiling range feedstream can havea boiling range from about 451° F. (about 233° C.) to about 800° C.(about 427° C.). Additionally or alternately, the feedstock can becharacterized by the boiling point required to boil a specifiedpercentage of the feed. For example, the temperature required to boil atleast 5 wt % of a feed is referred to as a “T5” boiling point. In oneembodiment, the mineral oil feedstock can have a T5 boiling point of atleast about 230° F. (about 110° C.), for example at least about 250° F.(about 121° C.) or at least about 275° F. (about 135° C.). Furtheradditionally or alternately, the mineral hydrocarbon feed can have a T95boiling point of about 775° F. (about 418° C.) or less, for exampleabout 750° F. (about 399° C.) or less or about 725° F. (about 385° C.)or less. In another embodiment, the diesel boiling range feedstream canalso include kerosene range compounds to provide a feedstream with aboiling range from about 250° F. (about 121° C.) to about 800° F. (about427° C.).

Catalyst for Catalytic Hydrothermal Processing

In various embodiments, hydrothermal processing can be performed in thepresence of a catalyst, such as one or a combination of catalysts, e.g.,those disclosed hereinbelow. In the embodiments described below, thecatalyst can be a supported catalyst suitable for use in thehydrothermal processing reaction environment and having any suitableparticle size and/or particle size distribution. Additionally oralternately, the catalyst can be a particulate catalyst with limited orsubstantially no solubility in the fluids present in the hydrothermalprocessing reaction environment.

One catalyst option can be to use a supported catalyst including a noblemetal (e.g., Pt, Pd, Rh, Ru, Ir, or a combination thereof). Additionallyor alternately, the support for the catalyst can be a hydrothermallystable support. Examples of suitable supports can include, but are notlimited to, refractory oxides such as titania and/or zirconia; silica;activated carbon; carbon on which is deposited one or more metalsselected from titanium, zirconium, vanadium, molybdenum, manganese, andcerium; magnesium oxides; hydrotalcites; other various types of clays;and combinations thereof, such as a mixture of two or more of titania,zirconia, and silica. Additionally or alternately, the support materialcan be substantially free of alumina. As used herein, “substantiallyfree” of alumina should be understood to mean less than 1 wt % alumina,preferably less than 0.1 wt % alumina, for example less than 0.01 wt %of alumina, completely no added alumina, or completely no alumina.

Another catalyst option can be to use a basic metal or mixed metal oxidewith or without a noble metal. Examples of such catalysts without anoble metal can include, but are not limited to, magnesium oxide,hydrotalcites, potassium supported on titania and/or zirconia, andcombinations thereof.

Still another catalyst option can be to use hydroprocessing type metalssupported on a suitable support. Examples of hydroprocessing type metalscan include, but are not limited to, a combination of a Group VIII metal(such as Co and/or Ni) with a Group VIB metal (such as Mo and/or W).Combinations of three or more Group VIII and/or Group VI metals canadditionally or alternately be used (e.g., NiMoW, CoNiMo, CoMoW, and thelike). Suitable support materials include those identified hereinabove.

In some embodiments, the catalyst metals can be present on the catalystin the form of an oxide or a sulfide. Additionally or alternately,catalyst metals can be present in a metallic state. Further additionallyor alternately, catalyst metals can be present on a support in anyconvenient form. Examples can include metal salts such as metalacetates, metal carbonates, or other organometallic forms.

Relative to the amount of algae, the amount of catalyst in the reactor(reaction zone) can be at least about 0.05 wt %, for example at leastabout 0.1 wt %, at least about 1 wt %, at least about 2.5 wt %, or atleast about 5 wt %. Additionally or alternately, the amount of catalystin the reactor (reaction zone) can be about 20 wt % or less relative tothe amount of algae, for example about 15 wt % or less or about 10 wt %or less.

The amount of metal supported on the catalyst can be varied. Relative tothe weight of the catalyst, the amount of noble metal supported on thecatalyst, when present, can be at least about 0.1 wt %, for example atleast about 0.5 wt %, at least about 0.6 wt %, at least about 0.75 wt %,or at least about 1.0 wt %, based on the total catalyst weight.Additionally or alternately, the amount of noble metal supported on thecatalyst, when present, can be about 1.5 wt % or less, for example about1.0 wt % or less, about 0.75 wt % or less, or about 0.6 wt % or less,based on the total catalyst weight. More generally, the amount ofmetal(s), individually or in mixtures, on the catalyst support can be atleast about 0.1 wt %, for example at least about 0.25 wt %, at leastabout 0.5 wt %, at least about 0.6 wt %, at least about 0.75 wt %, atleast about 1 wt %, at least about 2.5 wt %, or at least about 5 wt %,based on the total catalyst weight. Additionally or alternately, theamount of metal(s), individually or in mixtures, on the catalyst supportcan be about 35 wt % or less, for example about 20 wt % or less, about15 wt % or less, about 10 wt % or less, or about 5 wt % or less, basedon the total catalyst weight.

Additionally or alternately, the particle size for the catalystparticles can be varied, e.g., selected to facilitate separation of thecatalyst particles from other solids. In such an embodiment, thecatalyst particles can have an average particle size of at least about1000 μm, for example at least about 1500 μm or at least about 2000 μm.To achieve a desired catalyst particle size, catalysts can optionally beformulated to include a hydrothermally stable binder material, inaddition to the support material and any active metals, if present.Suitable hydrothermally stable binder materials can be similar tomaterials used as a support material and/or can include, but are notnecessarily limited to, an oxide of one or more metals selected fromsilicon, titanium, zirconium, vanadium, molybdenum, manganese, andcerium. For a supported catalyst that is formulated with a binder, thesupport material can function as a binder, or a different material canbe used as a binder.

Catalytic Hydrothermal Processing Conditions

In various embodiments, catalytic hydrothermal processing can beperformed in a batch, semi-batch, and/or continuous type processingenvironment(s). Regardless of whether the reaction takes place in abatch, semi-batch, or continuous reaction system, any system regionwhere the biomass is treated under hydrothermal treatment conditions canbe referred to as the reaction zone. The reaction zone can correspond toa reactor for a batch or semi-batch environment and/or to a reactor,conduit, or other location for hydrothermal treatment in a continuousreaction system.

In embodiments involving a batch reactor, the reactor can be any type ofbatch reactor suitable for handling the processing conditions. Due tothe potential presence of water at supercritical conditions, stainlesssteel can be a suitable non-reactive material for the reactor walls.Other materials and/or coatings for the reactor surfaces can be usedthat are compatible with the reaction conditions described herein.Examples of suitable reactors can include, but are not limited to,autoclaves, stirred tanks, plough mixers, and the like, and combinationsthereof. Alternately, a bubble column could be used. One possibleadvantage for batch or semi-batch type processing can occur for algaefeeds that have relatively poor flow characteristics. For example, at analgae concentration relative to water of about 20 wt % (i.e., about 4parts water to 1 part algae by weight), the resulting mixture can havethe consistency of a paste. Such a paste could be difficult to move,e.g., using pumps in a continuous flow type reactor.

In one embodiment, a batch reactor can be used for catalytichydrothermal processing of an algae feed. A portion of algae feed mixedwith water can be introduced into the reactor, which can then be purged(if necessary), e.g., to remove any oxygen containing gases. Optionally,a partial pressure of an inert gas and/or a reducing gas can then beintroduced into the reactor. Examples of suitable reducing gases caninclude hydrogen, while suitable inert gases can include nitrogen.Additional or alternate examples of suitable reducing gases can includeany gas that does not add molecular oxygen to the reaction atmosphere,whether prior to the start of the reaction or from dissociation formingoxygen during the hydrothermal processing. The partial pressure ofadditional gas introduced into the reactor, when present, can be atleast about 1 bar (about 0.1 MPa), for example at least about 25 bar(about 2.5 MPa), at least about 40 bar (about 4.0 MPa), or at leastabout 50 bar (about 5.0 MPa). Additionally or alternately, the partialpressure of gas introduced into the reactor, when present, can be about100 bar (about 10 MPa) or less, for example about 75 bar (about 7.5 MPa)or less or about 50 bar (about 5.0 MPa) or less. Note that introducing areducing gas can correspond to at least partially dissolving a reducinggas in the water (e.g., saturating the water) for the hydrothermaltreatment.

After introducing the algae, water, catalyst, and any additionalreducing and/or inert gases, the batch reactor can be sealed. Thetemperature of the reactor can then be raised to at least about 50° C.,for example at least about 80° C., at least about 100° C., at leastabout 150° C., at least about 200° C., at least about 250° C., at leastabout 275° C., or at least about 300° C. Additionally or alternately,the temperature of the reactor can be raised to about 500° C. or less,for example about 400° C. or less, about 380° C. or less, about 350° C.or less, about 300° C. or less, or about 275° C. or less. Furtheradditionally or alternately, the pressure in the reactor can be at leastabout 1 barg (about 0.1 MPag), for example at least about 4.5 barg(about 450 kPag), at least about 25 barg (about 2.5 MPag), at leastabout 40 barg (about 4.0 MPag), at least about 50 barg (about 5.0 MPag),or at least about 100 barg (about 10 MPag). Additionally or alternately,the partial pressure of gas introduced into the reactor, when present,can be about 300 barg (about 30 MPag) or less, for example about 250barg (about 25 MPag) or less, about 225 barg (about 22.5 MPag) or less,or about 200 barg (about 20 MPag) or less.

In some embodiments, the combination of pressure and temperature withinthe reactor can be selected so that the water in the reactorsubstantially does not undergo a phase change (e.g., completely does notundergo a phase change). In a phase diagram for water, the criticalpoint is located at a temperature of about 374° C. and a pressure ofabout 22 MPa. At temperature and pressure combinations beyond this pointin the phase diagram, water does not experience a phase transitionbetween a liquid phase and a gaseous phase. Instead, beyond the criticalpoint, water behaves as a single fluid phase. Thus, in some embodiments,the combination of pressure and temperature can be selected so that theliquid water in the reactor remains the stable phase until conditionsbeyond the critical point are achieved. One way of satisfying thiscondition can be to select reaction temperatures and pressures that areless than the critical point and thus that do not lead to a phasetransition. Note that in some embodiments, a partial pressure ofadditional gas can be introduced into the reactor (in which case, someminimal amount of water may become vapor, but this situation iscontemplated in the invention not to be a “substantial” phase change).If the partial pressure of additional gas is greater than about 22 MPa,then the pressure is already beyond the critical point for water andsubstantially no phase transition is possible. Note also that, in aclosed reactor, e.g., which can have a partial pressure of another gas,substantial phase transitions of water are not likely to occur, so longas the volume of liquid water is sufficient relative to the volume ofthe reactor.

Additionally or alternately, the pressure within a reactor can be set byselecting a temperature for the water. In some embodiments, the reactorcan be sealed or closed after introduction of water and any additionalgases, if present. A partial pressure of water vapor should develop inthe reactor to correspond to the temperature of the water in thereactor. As the temperature of the reactor increases, a correspondinghigher partial pressure of water should develop in the reactor. Thehydrothermal processing can be performed at a pressure that representsthe combination of the partial pressure of water at the reactiontemperature and the partial pressure of any additional inert and/orreducing gases, as well as the partial pressure of any gases generatedor evolved during processing. Examples of water partial pressures atvarious temperatures can include about 0.01 MPa at about 50° C.; about0.05 MPa at about 80° C.; about 0.1 MPa at about 100° C.; about 0.5 MPaat about 150° C.; about 1.6 MPa at about 200° C.; about 4.0 MPa at about250° C.; about 5.9 MPa at about 275° C.; about 8.6 MPa at about 300° C.;about 16.5 MPa at about 350° C.; and about 22.1 MPa at about 374° C.Because about 22.1 MPa and about 374° C. corresponds to the criticalpoint in the phase diagram for water, it is not meaningful to refer tothe partial pressure of “water vapor” in a reactor at temperaturesbeyond that point.

In some embodiments, the hydrothermal processing can be performed in acontinuous flow type reactor. An example of a continuous flow typereactor can be a pipe or other conduit that can be heated to raise thetemperature of the feed in the conduit to the desired hydrothermalprocessing temperature. For example, a conduit passing through a furnacecould be used, and/or a conduit surrounded by steam. The conduit canhave any convenient shape for passing through the heating zone. Forexample, a conduit having the shape of a spiral can be used to increasethe size of the portion of the conduit within the heating zone.

It has been noted that the amount of water needed in order to performhydrothermal processing may not be sufficient to provide the type offlow characteristics desired for a continuous flow environment. In acontinuous flow processing environment, one option for improving thefluid flow characteristics of the algae can be to increase the watercontent of the algae feed. However, increasing the water content canalso result in a corresponding decrease in the yield per volume of thereaction system, due to the reduction in the amount of algae in thefeed.

Other types of continuous flow reactors can potentially be used forhydrothermal treatment of an algae feed, such as a fixed bed reactor, amoving bed, an ebullating bed reactor, or the like. If a fixed bedreactor is used, one concern could be fouling of the catalyst bed, e.g.,due to solids present in the biomass or algae feed. Fouling of acatalyst bed can result in a higher than expected pressure drop across acatalyst bed, due to restrictions in flow of feed through the bed. Fixedbed reactors can often handle feeds with particle sizes up to about 150μm without significant fouling issues. Nevertheless, any fouling of acatalyst bed can be somewhat mitigated, e.g., by having bypass tubes tocontrol the pressure drop across the catalyst bed. Unfortunately,although individual algae cells have small diameters, relative to 150μm, hydrothermally treated algae can have an increased tendency toagglomerate. As a result, 5% or more of the algae based solids resultingfrom hydrothermal treatment of an algae feed can be in the form ofagglomerated particles with a particle size greater than 150 μm.Nevertheless, in some embodiments, a fixed bed reactor may be used,particularly when agglomerative behavior of the product algae solids canbe mitigated, e.g., by using a sufficient space velocity and/or throughother means.

As an alternative to a fixed bed reactor, an ebullating bed reactor canbe used for hydrothermal processing. In a conventional ebullating bedreactor, both the feedstock (water and algae) and a treat gas(hydrogen-containing reducing gas) can be introduced into the reactorfrom the bottom of the reactor. In such reactors, a recycled feedcontaining a portion of the reactor effluent can also be introduced intothe bottom of the reactor. These feed flows can travel up into thereactor and pass through a catalyst support grid designed to preventcatalyst from entering the areas at the bottom of the reactor where thefeed pumps are located. The catalyst in such ebullating bed reactors istypically located above the catalyst support grid.

When the feedstock (and optionally additional gas) flow(s) reach thecatalyst bed, the bed generally becomes fluidized, leading to expansionof the bed as well as mixing within the bed. The feed (and hydrogen) canreact within the bed to form products, including liquid products, solidproducts, and gaseous products. The flow in a conventional ebullatingbed reactor can continue upward until an effluent is drawn off at thetop. This effluent can be a combination of desired products, unreactedhydrogen (when present), and byproduct gases, including contaminantgases such as H₂S or NH₃ that may have formed during the reaction. Inpreferred embodiments, a portion of the liquid effluent can be recycled,e.g., to the bottom of the reactor. If desired, the gases can beseparated from the liquid portion of the effluent.

FIG. 1 schematically shows an example of a reactor suitable for use inan embodiment of the invention. In FIG. 1, hydrothermal processingreactor 100 can represent any type of reactor suitable for performing acatalytic hydrothermal process for treatment of an algae (or otherbiomass) feed. Input flows into reactor 100 can include a gas input 102,such as an inert gas input, a hydrogen gas input, another type ofreducing gas input, or a combination thereof. Another input flow can bean algae or biomass input 104. If algae input 104 has poor flowproperties, such as due to a sufficiently low water content, algae input104 may alternately represent a non-flow input, such as extrusion,pouring, or dumping of the algae input 104 into reactor 100. Optionally,a supplemental input flow 105 can be provided for various reasons. Oneoption for a supplemental input flow 105 can be to include additionalwater, so that hydrothermal processing conditions can be maintained. Anadditional or alternate component for supplemental input flow 105 can bean “inert” hydrocarbon stream (that can undergo minimal reaction underhydrothermal processing conditions) and/or a product recycle stream.Such a hydrocarbon stream and/or recycle stream could be used as acarrier for a catalyst or a catalyst precursor. As an alternative, algaeinput 104 and supplemental input 105 can be combined into a singlestream prior to entering the reactor 100. The hydrothermal treatment cangenerate an output flow 107, e.g., which can be a mixture of variousphases. Phases that can comprise output flow 107 can include a gasphase, a hydrocarbon based phase, an aqueous based phase, and one ormore solid phases. These phases may optionally be mixed with each other,such as mixing of the solids with the aqueous phase.

Separation of Products from Catalytic Hydrothermal Processing

Hydrothermal processing can result in a multi-phase product. Themulti-phase product can include a gas phase, a hydrocarbon or oil phase,and an aqueous phase that can include solids. The gas phase, oil phase,aqueous phase, and solids phase can be separated from each other by anyconvenient method, such as by use of a three phase separator.Characterization of the oil phase is described further below. In someembodiments, the solids phase can initially be together with aqueousphase. For example, the solids phase can be suspended in the aqueousphase or can be a precipitate slurried in and/or settling out of theaqueous phase. The solids phase can also be valuable, containing one ormore of: phosphorus and other potential nutrients for algae and/or othermicroorganisms; unreacted and/or only partially reacted biomass; andcatalyst particles; inter alia. In some embodiments, the catalystparticles can be separated from the other solids to allow for theirrecycle, as well as for recycle of the nutrients, if present.

Additionally or alternately, it can be desirable to regenerate catalystparticles prior to recycling catalyst particles to the reaction zone forfurther use in hydrothermal treatment. Catalyst particles can have atendency to accumulate additional material on the surface of thecatalyst, such as “coke” or other carbon based products. These carbonbased products can be removed from a catalyst, for example, by passingthe catalyst through an oxidizing atmosphere at elevated temperatures.Conventional methods and systems for regeneration of catalyst particlescan be used. Regeneration can be performed on all of the catalystrecovered from the product solids, or the regeneration can be performedon a portion of the recovered catalyst.

FIG. 2 shows a schematic example of a processing flow for an embodimentof the invention involving algae as the form of biomass for processing.In FIG. 2, an integrated scheme is shown where products from thecatalytic hydrothermal processing are recycled for further use. In FIG.2, the biomass input for the hydrothermal processing can be from analgae source. This algae can be produced by an algae growth process 210,which can include any convenient and/or known process. The algae can beharvested 220 for conversion into hydrocarbon products. As part of algaeharvesting 220, some amount of water can optionally be removed from thealgae. For example, water can be completely removed from the algae aspart of production of freeze-dried algae. Alternately, water can beremoved using only physical processes, such as by centrifuge, which canadvantageously result in an algae feed with a water to algae weightratio of about 10:1 or less, for example about 7.5:1 or less, or about5:1 or less. Additionally or alternately, the water to algae weightratio can be at least about 2:1, for example at least about 2.5:1, or atleast about 3:1. One advantage of performing only a partial separationof algae and water can be that less energy is needed to perform only apartial separation, as compared to complete separation.

After harvesting, the harvested algae can be used as a feed forhydrothermal processing 230. The algae feed can be optionally combinedwith a catalyst, a partial pressure of gas such as hydrogen, andoptionally water, e.g., if sufficient water is not included with thealgae feed. The hydrothermal processing 230 can generate a variety ofproducts. An initial separation of these products can be performed inthree-phase separator 240. Three-phase separator 240 can be used togenerate a gas phase product 242, a hydrocarbon or oil product 248, anda product including water and various solids 246. The gas phase product242 can include hydrogen, inert gases that may have been present duringhydrothermal processing 230, product gases from the hydrothermalprocessing 230 (such as CO₂, CO, H₂S, NH₃, and the like, andcombinations thereof), and low boiling hydrocarbons produced duringcatalytic hydrothermal processing 230. The low boiling hydrocarbons caninclude hydrocarbons that are gases at room temperature (such asmethane, ethane, or the like, or combinations thereof) and/orhydrocarbons that are gases at the temperature of the three-phaseseparation. If the three-phase separation is performed at an elevatedtemperature, this could include higher boiling aliphatic hydrocarbonsand/or other species (such as methanol). Note that some of the aboveproducts may be at least partially solubilzed in the water phase, suchas the product gases from the hydrothermal processing.

In the products from hydrothermal processing 230, the desiredhydrocarbon or oil product can form a phase separate from an aqueousphase containing various solids. These distinct phases can be separatedin three-phase separation 240. The resulting hydrocarbon product 248 canrepresent the desired oil product from the catalytic hydrothermaltreatment. The hydrocarbon product 248 may, if desired, undergo avariety of additional processing, which can include an optionaldistillation 260 to isolate desired boiling ranges 262 and 263 of theproduct and/or hydroprocessing to upgrade the hydrocarbon product 248 ora distillation cut 262 or 263 for use. Additionally or alternately, atleast a portion of hydrocarbon product 248 and/or of distillation cut(s)262 and/or 263 may optionally be recycled to hydrothermal processing230, e.g., for combination with the algae/water input feed, which mayimprove the input feed flow characteristics.

In some embodiments, the water and solids 246 from the three-phaseseparation 240 can include several types of solids, which can includebut are not limited to solids derived from the algae, solids comprisingphosphorus and/or various metals, unreacted and/or partially reactedbiomass, and catalyst particles. The water and solids 246 can be furtherprocessed in solids separation 250 to separate the solids for furtheruse. Solids separation 250 can generate an aqueous stream 257, catalystparticles 253, and algae-derived solids 259. Note that separation of thecatalyst particles from the algae-derived solids may occur prior toseparation of the aqueous phase from the solids. In a preferredembodiment, the catalyst particles 253 can be returned to the catalytichydrothermal processing for further use. Additionally or alternately,the algae-derived solids 259 can be returned to the algae growth process210, e.g., as raw material for developing a new batch of algae feed.Further additionally or alternately, at least a portion of aqueousstream 257 and/or of the water from water and solids 246 can be recycledto the algae growth process 210, e.g., to provide additional nutrientssuch as nitrogen-containing species (like NH₃).

Although the scheme in FIG. 2 implies a series of processes locatedtogether, the algae growth 210 and harvesting 220 could take place at alocation remote from the catalytic hydrothermal processing 230. In suchan embodiment, several of the arrows in FIG. 2 could represent transportsteps, such as transport of the harvested algae to the location forcatalytic hydrothermal processing and/or transport of the algae-derivedsolids to the algae growth site.

Particle Sizes in Solids Product

One consideration for using physical separation processes on the solidsproduct can be the particle size of various portions of the solidsproduct. Depending on the embodiment, the solids product can includecatalyst particles, algae (or other biomass) based product, andunreacted or partially reacted algae or other biomass. The variousportions of the solids product can have different characteristicparticle sizes and/or particle size distributions.

Individual algae cells typically have a relatively small size. However,algae cells also have a tendency to agglomerate. As a result, theapparent particle size of a group of algae cells can be on the order ofabout 10 μm. As an example, the particle size distribution of a sampleof freeze-dried Nannochloropsis algae was determined using laserdiffraction techniques. Based on the laser diffraction study, it wasdetermined that roughly 50 vol % of the sample had a particle size ofless than about 13 nm, and nearly all of the particles had a particlesize of less than about 200 nm. This is shown in FIG. 5 as the “Noprocessing” line in the figure.

The particle size was also determined for a sample of freeze-driedNannochlropsis algae that had been processed by a non-catalytichydrothermal treatment at about 300° C. for about 1 hour. Afterhydrothermal treatment, the algae product solids showed an increase inproduct size. Roughly 50 vol % of the particles of the hydrothermaltreatment product solids had a particle size of about 200 μm or less,with an upper end to the particle size distribution that approachedabout 800 μm. This is shown as the “Hydrothermal Processing” line inFIG. 5.

Based on FIG. 5, one way to facilitate separation of catalyst particlesfrom other product solids from hydrothermal treatment can be to selectcatalyst particles with particle sizes greater than about 1000 μm, forexample greater than about 1500 μm or greater than about 2000 μm. Thiscan provide a particle size distinction relative to both reacted andunreacted algae solids. Based on the particle size distinction, catalystparticles can be separated from other product solids by filtration.Additionally or alternately, the catalyst particles can be separatedusing a hydrocyclone separator. Further additionally or alternately,catalyst particles can be separated using other separation methods thatare sensitive to particle size for separation.

In various embodiments, different metrics can be used to characterizethe size of a particle. One option for characterizing the size of aparticle can be to select particles with an average particle sizegreater than about 1000 μm, for example greater than about 1500 μm orgreater than about 2000 μm. Methods for determining particle size areknown in the art.

Additionally or alternately, the size of a particle can be characterizedby selecting particles with a minimum average particle dimension greaterthan about 1000 μm, for example greater than about 1500 μm or greaterthan about 2000 μm. Using a minimum average particle dimension can behelpful for characterizing particles that have different dimensionsalong different axes of the particle. For example, a particle having aroughly spherical shape can be compared with a particle having a rod orcylinder type shape. A particle with a roughly spherical shape can havesimilar dimensions along any axis used to measure the particle. From thestandpoint of filtering the particle, the average particle size can beused to determine an appropriate size for filtering. By contrast, aparticle with a rod shape can have a size along one axis that issubstantially larger than the size along other axes of the particle. Afiltering method based on the long dimension of such a particle might beonly partially effective, as the particle might be able to pass throughthe filter in some orientations. For particles with different dimensionsalong different axes, a minimum average particle dimension can be auseful method of characterization.

Phosphorous Content in Solids Fraction

Additionally or alternately to recovery of a hydrocarbon product,recovery of other algae solids (or other biomass solids) can bebeneficial. For example, phosphorus can be recovered from the residualalgae solids after hydrothermal treatment. One potential use forrecovered phosphorus can be as a nutrient for growth of additional algaeor other biomass.

Improving the recovery of phosphorus from hydrothermal processing ofbiomass can involve balancing several factors. One benefit of variousembodiments can be that phosphorus forms a solid product, e.g., that canbe filtered out from the liquid product streams. Any phosphorus thatremains as part of the liquid hydrocarbon product and/or any phosphorusthat becomes solubilzed in a solvent could be recovered in one or moreseparate, additional processes. In the discussion below, the recovery ofphosphorus from products of hydrothermal treatment can be evaluatedbased on the amount of phosphorus recovered as solids.

Because the recovery of phosphorus can be evaluated based on the amountof phosphorus in the solids product, an initial goal can be to developprocessing conditions that result in a large percentage of phosphorus inthe solids product. One conventional way of processing a biomass feed,such as an algae feed, can be to extract a desired hydrocarbon productfrom the feed using an extraction solvent (e.g., such as a mixture ofCHCl₃ and CH₃OH). An extraction solvent can advantageously produceyields of phosphorus in the solids product of greater than 90 wt %relative to the amount of phosphorus in the feed. For an efficientphosphorus recovery process, it can be desirable to have a phosphorusyield in the solids product, relative to the feed phosphorus content, ofat least 80 wt %, for example at least 85 wt % or at least 90 wt %.

One option for improving the yield of phosphorus in the solids productcan be to increase the amount multivalent cations in the hydrothermalreaction. Many biomass feeds can contain at least some multivalentcations, such as Ca, Mg, and/or Fe. These multivalent cations can formphosphates or other phosphorus solids as part of the solids product. Forsome feeds, increasing the amount of available multivalent cations mayincrease the amount of phosphorus in the solids product, such as byadding extra cations selected from Ca, Mg, Fe, Al, or a combinationthereof. In some such embodiments, sufficient multivalent cations can beadded to provide at least about a 1:1 molar ratio of multivalent cationsto phosphorus atoms. This can correspond to adding at least about 0.1 wt%, for example at least about 0.2 wt % or at least about 0.3 wt % of amultivalent metal. Additionally or alternately, the amount of addedmultivalent metal can be about 1.0 wt % or less, for example about 0.8wt % or less, about 0.6 wt % or less, or about 0.5 wt % or less. Notethat the amount of multivalent metal can be reduced in a feed thatalready contains some multivalent metal.

Another consideration in selecting conditions for hydrothermalprocessing can be the relative amount of phosphorus in the solidsproduct. As noted above, solvent extraction can produce a solids productthat has greater than 90 wt % of the initial phosphorus in the feed.Unfortunately, such conventional solvent processing can also result in arelatively large amount of carbonaceous solids, e.g., in which productphosphorus can be present in amounts as low as 5 wt % or below. This canpresent a number of problems. First, additional processing can berequired to extract the phosphorus from the much larger proportion ofcarbon solids and/or other solids. Another problem can be thatrelatively high carbon content in the solids product can increase thedifficulty of using/selling the solids for an economically valuablepurpose. Another concern can be that a large proportion of carbon in thesolids product can mean that a noticeable amount of carbon may be lost,rather than being converted into a desired product.

The amount of phosphorus recovered in the solids product relative tocarbon can depend in part on the reaction conditions. Without beingbound by any particular theory, it is believed that relatively lowseverity reaction conditions can lead to incomplete reaction of thebiomass feed. This can result in algae (or other biomass) solids thatare unreacted and/or only partially reacted. The algae is initiallysolid, so unreacted and/or partially reacted algae can still be a solidafter an incomplete reaction. The unreacted and/or partially reactedalgae can thus add to the carbon content of the solids product, whichcan therefore reduce the ratio of phosphorus to carbon. It is noted thatincomplete reaction may additionally or alternately lead to a reductionin the amount of phosphorus in the solids relative to the initial amountof phosphorus.

Also without being bound by theory, it is believed that reactionconditions that are too severe may lead to increased carbon in thesolids product. Hydrothermal processing of biomass feeds can lead toincreased production of some heavier molecules, including aromatics. Aportion of these heavier molecules can correspond to insoluble compoundsthat tend to form solids. These additional solids can thus contribute tolowering the ratio of phosphorus to carbon in the solids products.

In some embodiments, the hydrothermal processing temperature can beselected to improve the ratio of phosphorus to carbon in the solidsproduct. For example, the reaction temperature can, in on embodiment,range from about 275° C. to about 325° C. Additionally or alternately incatalytic hydrothermal processing embodiments, the presence of catalystcan reduce the processing temperature that leads to an increase in theratio of phosphorus to carbon in the solids product. In suchembodiments, the reaction temperature can range from about 250° C. toabout 300° C.

Further additionally or alternately, improving the ratio of phosphorusto carbon in the solids product for catalytic hydrothermal processingcan be based on a combination of processing temperature and reactiontime. For example, for a processing time from about 60 minutes to about105 minutes, the reaction temperature can be from about 225° C. to about275° C.; for a processing time from about 45 minutes to about 90minutes, the reaction temperature can be from about 250° C. to about300° C.; for a processing time from about 30 minutes to about 60minutes, the reaction temperature can be from about 275° C. to about325° C.; for a processing time from about 24 minutes to about 48minutes, the reaction temperature can be from about 285° C. to about335° C.; for a processing time from about 15 minutes to about 30minutes, the reaction temperature can be from about 300° C. to about350° C.; and for a processing time from about 6 minutes to about 24minutes, the reaction temperature can be from about 325° C. to about375° C. It is noted that, in a continuous reaction environment, areaction time can more accurately be described in terms of a residencetime or a space velocity.

Evaluation of Hydrocarbon Products from Catalytic HydrothermalProcessing

Catalytic hydrothermal processing can be used to extract varioushydrocarbon fractions from an algae (or other biomass) feed. One exampleof a hydrocarbon fraction that can be extracted from an algae feed caninclude and/or be a distillate fraction. In the discussion below, adistillate fraction refers to a fraction that has a boiling rangebetween about 193° C. and about 360° C., or alternately to a fractionhaving at least 90 wt % of its boiling range between about 193° C. andabout 360° C. (e.g., the T5 could be about 193° C. and the T95 about360° C., or the T2 could be about 193° C. and the T98 about 360° C., orthe like).

One way to evaluate the products of a hydrothermal treatment process,whether catalytic or non-catalytic, can be to consider the hydrocarbonyield from the process. A total yield can be defined for a hydrothermaltreatment process based on the weight of hydrocarbon product capturedrelative to the initial weight of the algae or other biomass. Adistillate yield can also be defined for a hydrothermal treatmentprocess. One yield characterization can be the total distillate boilingrange yield for a process relative to the starting weight of algae orbiomass. Another characterization can be the percentage of distillateproduced relative to the total hydrocarbon yield.

An additional or alternate way to evaluate the products of ahydrothermal treatment process can be based on the levels of variousimpurities in the products. In a non-catalytic hydrothermal treatmentprocess (or in a catalytic hydrothermal process, analyzed on acatalyst-free basis), the hydrocarbon products can tend to incorporateimpurities such as nitrogen, oxygen, carbon-carbon double bonds, andaromatic groups. Thus, the percentage of heteroatoms (nitrogen and/oroxygen) in the total hydrocarbon product and/or the distillate productcan be of interest. The percentage of carbon-carbon double bonds andaromatic groups can be measured using techniques such as ¹³C NMR, and/orother metrics can be used such as the ratio of hydrogen to carbon in theproducts.

Additional Embodiments

Additionally or alternately, the present invention can include one ormore of the following embodiments.

Embodiment 1

A method for hydrothermally processing biomass, comprising: contactingan algae based feed with water in the presence of catalyst particlesunder effective hydrothermal processing conditions to produce amulti-phase product, the catalyst particles including a catalyst metaland having a minimum average particle dimension of at least about 1000μm; separating the multi-phase product to produce at least a gas phaseportion, a liquid hydrocarbon portion, an aqueous portion, and a solidsportion, the solids portion containing the catalyst particles and algaebased solids; and separating the catalyst particles from the algae basedsolids.

Embodiment 2

A method for hydrothermally processing biomass, comprising: contactingan algae based feed with water in the presence of catalyst particlesunder effective hydrothermal processing conditions to produce amulti-phase product, the catalyst particles including a catalyst metaland having an average particle size of at least about 1000 μm;separating the multi-phase product to produce at least a gas phaseportion, a liquid hydrocarbon portion, an aqueous portion, and a solidsportion, the solids portion containing the catalyst particles and algaebased solids; and separating the catalyst particles from the algae basedsolids.

Embodiment 3

The method of any one of the previous embodiments, wherein the averageparticle size of the catalyst particles is at least about 2000 μm.

Embodiment 4

The method of any one of the previous embodiments, wherein the supportfor the catalyst particles comprises a hydrothermally stable supportmaterial and the catalyst particles optionally further comprise ahydrothermally stable binder.

Embodiment 5

The method of embodiment 4, wherein the catalyst particles comprisetitania and/or zirconia.

Embodiment 6

The method of embodiment 4 or embodiment 5, wherein the support for thecatalyst particles includes 0.1 wt % or less of alumina

Embodiment 7

The method of any one of the previous embodiments, wherein the catalystmetal comprises Co, Ni, Mo, or a combination thereof, or wherein thecatalyst metal comprises Pt, Pd, Rh, Ru, Ir, or a combination thereof.

Embodiment 8

The method of any one of the previous embodiments, wherein the catalystmetal is in the form of an oxide or a sulfide

Embodiment 9

The method of any one of the previous embodiments, wherein the effectivehydrothermal processing conditions include a temperature from about 150°C. to about 500° C., for example from about 250° C. to about 375° C.,and a pressure from about 4.5 barg (about 45 kPag) to about 300 barg(about 30 MPag), and wherein the effective hydrothermal processingconditions optionally include a partial pressure of reducing gas(hydrogen) of at least about 2 bar (about 0.2 MPa).

Embodiment 10

The method of any one of the previous embodiments, wherein the catalystparticles are separated from the algae based solids prior to or duringseparation of the solids portion from the aqueous portion.

Embodiment 11

The method of any one of the previous embodiments, wherein contactingthe algae based feed with water under effective hydrothermal processingconditions does not result in a phase change for the water.

Embodiment 12

The method of any one of the previous embodiments, wherein the weightratio of water to algae is from about 2:1 to about 10:1, for examplefrom about 3:1 to about 5:1.

Embodiment 13

The method of any one of the previous embodiments, wherein the catalystparticles are present in an amount from about 1 wt % to about 20 wt %,based on a weight of the algae.

Embodiment 14

The method of any one of the previous embodiments, further comprisingseparating the hydrocarbon liquid product to produce a fraction havingat least 90% of its boiling range between about 193° C. and about 360°C.

Additionally or alternately, a method according to any one of theprevious embodiments can be provided, wherein the biomass feed has aphosphorus content and a phosphorus to carbon ratio, wherein theeffective hydrothermal treatment conditions are selected so that thesolids portion contains at least about 80%, for example at least about90%, of the phosphorus content of the biomass feed, and wherein thephosphorus to carbon molar ratio of the solids portion can optionally beat least about 0.25.

Additionally or alternately, a method according to any one of theprevious embodiments can be provided, wherein the effective hydrothermaltreatment conditions can comprise a temperature from about 250° C. toabout 300° C., for example from about 275° C. to about 325° C., fromabout 300° C. to about 350° C., or from about 325° C. to about 375° C.

Additionally or alternately, a method according to any one of theprevious embodiments can be provided, wherein the effective hydrothermaltreatment conditions can comprise hydrothermal treatment in the presenceof a catalyst, the temperature being from about 250° C. to about 300° C.and the processing time being from about 0.75 hours to about 1.5 hours,or the temperature being from about 275° C. to about 325° C. and theprocessing time being from about 0.5 to about 1.0 hours, or thetemperature being from about 300° C. to about 350° C. and the processingtime being from about 0.25 hours to about 0.5 hours.

Example of Catalytic Hydrothermal Treatment

A series of experiments were performed to test various types ofhydrothermal treatment of an algae feed. In the experiments, samples ofalgae feed were placed in 316SS stainless steel 1 inch outer diameterreactors (Swagelok cap and plug). The reactor was placed into apre-heated ebullated sandbath. The reactors remained in the sandbath forabout 60 minutes. At the end of the time period, the reactors wereremoved from the sandbath and quenched to room temperature. Thehydrocarbon products were recovered using methylene chloride extractionand phase separation.

A commercially available sample of freeze-dried Nannochloropsis algaewas used for the experiments. The algae were mixed with water to yield awater to algae weight ratio of about 4:1. For experiments involving acatalyst, the amount of catalyst added to the reactor was about 10% byweight, relative to the weight of the dried algae. In experimentswithout a catalyst, a nitrogen partial pressure of about 3 bar (about0.3 MPa) was added to the reactor. In experiments with a catalyst, apartial pressure of about 50 bar (about 5.0 MPa) of hydrogen was addedto the reactor. In the experiments described below, the temperature ofthe sandbath (and therefore the reactor) was either about 300° C. orabout 350° C.

Table 1 shows examples of hydrothermal processing of algae samples at aseries of reaction conditions. As shown in Table 1, hydrothermalprocessing was performed without a catalyst, with catalysts of Ptsupported on activated carbon (about 10 wt % Pt), with catalysts of Pdsupported on activated carbon (about 10 wt % Pd), an activated carboncatalyst, and Pt supported on niobic acid (about 10 wt % Pt).

TABLE 1 Total Std % % Distillate % Catalyst Yield Dev distillateincrease Yield increase None 39.6 44.4 17.6 (350° C.) Pt/C 31.5 2.1 53.821.2 16.9 −4.0 (350° C.) Carbon 35.0 48.5 9.2 13.5 −23.3 (350° C.)Pt/niobic acid 31.9 0.1 53.7 20.9 17.1 −2.8 (350° C.) None 44.4 49.221.9 (300° C.) Pt/C 27.3 3.0 56.4 14.6 15.4 −29.7 (300° C.)

As shown in Table 1, performing hydrothermal processing in the presenceof a catalyst had several impacts on the products. The overall yield ofhydrocarbon product was reduced, but the percentage of distillateproduct in the overall yield was increased. The net effect was that thetotal distillate yield was also decreased, although this decrease wassmall for the catalysts including Pt at about 350° C.

FIGS. 4 a and 4 b show an example of how the yield profile changes forprocessing with no catalyst versus processing in the presence of thecatalyst with about 10 wt % Pt supported on carbon. FIGS. 4 a and 4 bprovide the derivative of a thermogravimetric analysis (TGA) profile atboth about 300° C. (FIG. 4 a) and about 350° C. (FIG. 4 b) for the nocatalyst and Pt/carbon catalyst runs shown in Table 1. In the plotsshown in FIGS. 4 a and 4 b, it was assumed that the mass loss was due toboiling as opposed to decomposition. As shown in FIGS. 4 a and 4 b, thecatalytic hydrothermal processing produced an increased amount ofhydrocarbon products both below about 193° C. and between about 193° C.and about 360° C. The increase in the amount of lower boiling productswas more pronounced at a processing temperature of about 300° C.

In addition to modifying the overall yield, performing the hydrothermalprocessing in the presence of a catalyst also modifies the impuritieswithin the hydrocarbon product. Table 2 shows results from ¹³C NMRcharacterization of the hydrocarbon products for processing at about350° C. with various catalysts. In Table 2, “HT” refers to hydrotalcite.For the experiment using both Pd supported on carbon and hydrotalcite,10% by weight of each catalyst, based on the weight of the algae, wasincluded in the reactor.

TABLE 2 ¹³C NMR Yield ¹³C NMR Aromatics/ ¹³C NMR Catalyst Oil (%) C═OOlefins Aliphatics None 39.6 8.3 37.7 54 Pd/C and HT 43.3 5.5 25.0 70.0(10 wt % each) Carbon 35.0 7.8 21.6 70.6 Pt/C 31.5 1.3 28.0 70.7Pt/niobic acid 31.9 6.8 26.9 70.6

Based on the data in Table 2, all of the catalysts were effective forreducing the total level of impurities in the hydrocarbon productsproduced by hydrothermal processing of algae. The Pt on carbon catalystwas the most effective for reducing the percentage of oxygen containingspecies in the hydrocarbon products. The carbon catalyst was mosteffective for reducing the percentage of aromatics and olefins in thehydrocarbon products. All of the catalysts tested provided similarresults for increasing the amount of aliphatics in the hydrocarbonproducts. The data in Table 2 may also indicate that increasing therelative amount of catalyst in a reactor can improve the hydrocarbonproducts. Using 10% by weight of both a Pd on carbon catalyst and ahydrotalcite catalyst resulted in both an increased hydrocarbon yieldand a reduced level of impurities in the hydrocarbon products. Based onthe data in Table 2, another useful catalyst combination may be asupported Pt on carbon catalyst in combination with a hydrotalcite oranother type of catalyst, such as one containing magnesium oxide.

Use of a catalyst in the presence of a hydrogen-containing atmospherecan also increase the amount of hydrogen present in the resulting oilproduct. Table 3 shows the hydrogen to carbon ratio and nitrogen contentof the hydrocarbon products from several experiments.

TABLE 3 Catalyst Yield Oil (wt %) H/C (molar ratio) N (wt %) None 39.61.4 5.5 Pd/C and HT 43.3 1.7 3.5 (10 wt % each) HT 33.8 1.6 5.7 Carbon35.0 1.6 4.7 Pt/C 31.5 1.8 4.6

As shown in Table 3, hydrothermal processing in the presence of acatalyst and an atmosphere containing hydrogen led to an increase in thehydrogen to carbon ratio for the resulting hydrocarbon products. Theincrease in the hydrogen to carbon molar ratio was consistent with thedata from Table 2, which showed increases in aliphatic carbon speciesand decreases in compounds with double bonds or aromatic rings. Thecatalysts with carbon, Pt on carbon, and the combination of Pd on carbonwith hydrotalcite also showed reduction in the amount of nitrogencontained within the hydrocarbon products. This was beneficial, as suchresults indicated a reduced amount of, or necessity for, additionalprocessing needed to make a suitable diesel or lubricant product.

Processing of Product Solids for Recycle of Nutrients

As noted above, some of the product solids can be recycled for use asnutrients for growth of further algae or other biomass. An example ofthis type of recycle can be recycling of phosphorus compounds. In orderto recycle the phosphorus, the phosphorus can be converted from thesolid form into a precursor form that can be readily processed into asuitable nutrient. An example of this type of conversion can beconversion of phosphorus in the product solids into a more easilydistributable form, such as phosphoric acid. The phosphoric acid canthen be used either as a nutrient, or as a precursor or reagent to makea suitable nutrient.

Phosphorus can be contained in the product solids in a variety of forms,such as phosphates and/or phosphites, and may be coordinated by Ca, Mg,or other multivalent cations. The solids can also contain carboncompounds. In order to separate the phosphorus from the carbon, thephosphorus in the solids can, in one embodiment, be converted tophosphoric acid. Conversion of phosphorus to phosphoric acid is a knownreaction, and can be performed by treating the phosphorus containingsolids with sulfuric acid. The sulfuric acid can react with thephosphorus to form phosphoric acid. The sulfate ions from the sulfuricacid can combine with Ca or Mg cations and precipitate out. In suchsituations, the carbon may remain as additional solid product. Thesulfate solids and carbon can be separated from the phosphoric acid byphysical and/or known/conventional means, e.g., using filtration or asettling pond.

Examples of Phosphorous Recovery

A series of experiments were performed to test phosphorus recovery fromconventional solvent processing of an algae feed and from hydrothermaltreatment of an algae feed. A commercially available freeze-driedNannochloropsis algae sample was used for the experiments.

For the solvent processing, the solvent was a 50:50 mixture on a volumebasis of CHCl₃ and CH₃OH. One part of the freeze-dried Nannochloropsisalgae was combined with five parts of the CHCl₃/CH₃OH solvent andvigorously stirred for about 24 hours at room temperature (i.e., about20-25° C.). Two distinct phases were apparent, a first phase containingthe solvent and a solubilzed product, and a second phase containingsolid remnants suspended in and/or settled to the bottom of the solvent.The solids remnants were isolated and analyzed; the results of thesecharacterizations are shown in Table 4 below.

For the hydrothermal treatment experiments, samples of the freeze-driedalgae were mixed with water in a ratio of about four parts water to onepart algae. The algae and water mixture was placed in 316SS stainlesssteel ˜1-inch outer diameter reactors (Swagelok cap and plug). Anitrogen partial pressure of about 50 bar (about 5.0 MPa) was added tothe reactor. A separate catalyst was not added to the reactor. Thereactor was placed into a pre-heated ebullated sandbath. The reactorsremained in the sandbath for about 60 minutes. Thereafter, the reactorswere removed from the sandbath and quenched to approximately roomtemperature. The hydrocarbon products were recovered using methylenechloride extraction and phase separation. In the experiments describedbelow, the temperature of the sandbath (and therefore the reactor) wasabout 200° C., about 300° C., or about 350° C.

Table 4 shows examples of processing of algae samples using solventextraction and at the three hydrothermal processing temperatures. In thetable, the term “phosphorus yield” refers to the weight percent ofphosphorus from the initial sample that was contained in the solidsproduct. Phosphorus concentration refers to the weight percent ofphosphorus in the solids product. The P/C molar ratio refers to themolar ratio of phosphorus to carbon in the solids product. Thephosphorus recovery efficiency is a measure of the relative amounts ofphosphorus and carbon in the solids product. The phosphorus recoveryefficiency is defined asP_(recov eff)=P_(yield)×[P_(moles)/(P_(moles)+C_(moles))].

In Table 4, Column A shows the results from analysis of the productsolids from the solvent extraction. Columns B, C, and D show the resultsfrom analysis of the solids fraction from the hydrothermal treatments atabout 200° C., about 300° C., and about 350° C., respectively.

TABLE 4 A B C D (Solvent only) (200° C.) (300° C.) (350° C.) P Yield (%)97 34 91 95 P Conc. (wt %) 1.55 2.16 30.8 21.8 P/C molar ratio 0.0140.015 0.56 0.26 P recovery 1.3 0.5 32.5 19.8 effic. (%)

As shown in Table 4, solvent extraction resulted in a relatively highphosphorus yield in the solids product of 97%. However, the solidsproduct also included a large amount of other material, as shown by theoverall weight percentage of phosphorus (1.55%). A large portion of thisadditional material was carbon, as shown by the phosphorus to carbonmolar ratio (0.014). As a result, the phosphorus recovery efficiency, asdefined above, was only 1.3%.

For the hydrothermal processing at about 200° C., the phosphorus yieldwas lower at about 34%. Because of the low initial recovery, and arelatively low concentration of phosphorus in the solids, the phosphorusrecovery efficiency at about 200° C. was less than 1%.

At the higher processing temperatures, the phosphorus recoveryefficiency was notably higher. At both ˜300° C. and ˜350° C., thephosphorus yield was greater than about 90%, indicating a good captureof the initial phosphorus in the solids product. Both the ˜300° C. and˜350° C. experiments showed dramatically improved phosphorus recoveryefficiencies, relative to the solvent extraction. This was due in partto the lower carbon content of the solids product, as the phosphorus tocarbon molar ratio at both ˜300° C. and ˜350° C. was greater than about0.25.

Additionally, the experiment at about 300° C. showed an unexpectedlyimproved result even relative to the experiment at about 350° C.Although the experiment at ˜300° C. had a slightly lower phosphorusyield, the amount of carbon and other materials in the solids productwas dramatically lower, as shown by the ˜30.8 wt % phosphorusconcentration and the phosphorus to carbon molar ratio of ˜0.56. Withoutbeing bound by any particular theory, it is believed that the additionalcarbon present in the solids product at ˜350° C. may be due to excessreaction with the feed. In an embodiment, the additional improvedphosphorus recovery efficiency shown here at a ˜300° C. processingtemperature can be maintained for other feeds and at other reactionconditions by selecting reaction conditions that maintain a phosphorusyield of around 90%, such as a phosphorus yield from about 87% to about93%.

The solids product generated by the experiment at ˜300° C. was alsoanalyzed using X-ray diffraction (XRD). Compounds that could beidentified from the XRD spectrum included phosphates and phosphites.Some compounds identified in the scan were Ca₁₈Mg₂H₂(PO₄)₁₄;Ca_(28.8)Fe_(3.2)(PO₄)₂₁O_(0.6); Mg(PO₃)₂; Ca₂P₂O₇; and CaCO₃.

Prophetic Example of Catalyst Recovery

An algae feed is processed under hydrothermal treatment conditions. Thereaction zone can be a batch reactor, a semi-batch reactor, or acontinuous flow system in which the reaction zone for the hydrothermaltreatment can include a coiled conduit surrounded by an oven. Thecoiling of the conduit increases the path length of the conduit withinthe oven. The flow rate within the conduit is selected so that feed hasa residence time within the reaction zone of about 15 minutes.Alternatively, if the batch option is used, the batch hydrothermaltreatment is performed for about 15 minutes. The temperature in thereaction zone is about 350° C. The feed in the reaction zone includes amixture of algae and water with a water to algae weight ratio of fromabout 10:1 to about 2.5:1. The feed also includes 10 wt % of a supportedcatalyst, such as a supported CoMo catalyst or a supported Group VIIInoble metal catalyst. The support and/or binder for the catalyst can bea non-alumina, such as titania and/or zirconia. The particle size forthe catalyst particles is about 1500 μm. The pressure in the reactionzone is determined in part by the vapor pressure of water at thereaction temperature. The pressure is also increased by the addition of2.5 MPa of hydrogen gas. The hydrothermal treatment reaction productsare passed from the reaction zone as a flow into a separator. A gasphase product, a hydrocarbon product, an aqueous product, and a solidsproduct are separated out. The hydrocarbon product can have an improveddistillate yield relative to hydrothermal treatment under similarconditions without a catalyst. The resulting distillate can also have areduced concentration of aromatics, olefins, and/or carbonyl groupsrelative to hydrothermal treatment under similar conditions without acatalyst. The solids product can be in the form of a solids suspended inthe aqueous product. The solids product suspended in the aqueous productcan then be filtered using filter mesh with an about 1000 μm size. Thealgae based reaction products (such as phosphorus containing solids) aswell as any unreacted algae can pass through the filter. The catalystparticles are retained on the retentate side of the filter. The catalystparticles can then be recycled to the reaction zone for furtherhydrothermal treatment. Optionally, as necessary, the catalyst particlescan be passed through a regenerator, such as a furnace with an oxidizingatmosphere, prior to being recycled to the reaction zone.

Hydroprocessing—Hydrotreating, Dewaxing, and Hydrofinishing

In some embodiments, additional hydroprocessing can optionally beperformed after hydrothermal processing. For example, a hydrotreatmentprocess can remove oxygen, sulfur, and/or nitrogen from a feedstock,such as a product generated by hydrothermal processing. A hydrotreatmentprocess can additionally or alternately saturate aromatics and/orolefins. Further additionally or alternately, catalytic dewaxing can beperformed on a hydrocarbon fraction, such as one generated byhydrothermal processing, which can improve one or more cold flowproperties of the so-treated hydrocarbon fraction. Still furtheradditionally or alternately, hydrofinishing can be performed on ahydrocarbon fraction, such as one generated by hydrothermal processing.Hydrofinishing can be used to (additionally) saturate olefins and/oraromatics in a feed.

A hydrotreatment process can be used to hydrotreat a hydrocarbonfraction from a hydrothermal treatment process, or a mixture of such ahydrocarbon fraction with a mineral feed, a biocomponent feed, or acombination thereof. In an embodiment, a mineral and/or otherbiocomponent portion of a feed can be hydrotreated separately from ahydrothermally treated portion of a feed. Alternately, a mineral portionand/or biocomponent portion can be mixed together with a hydrothermallytreated hydrocarbon fraction for hydrotreatment.

A conventional hydrotreatment catalyst can contain at least one of GroupVIB and Group VIII metals on a support such as alumina and/or silica.Examples of such conventional catalysts can include supported NiMo,CoMo, and NiW catalysts. Hydrotreating conditions can, in oneembodiment, be selected to be similar to the dewaxing conditions notedherein. Alternately, the hydrotreating conditions can include atemperature from about 315° C. to about 425° C., a total pressure fromabout 300 psig (about 2.1 MPag) to about 3000 psig (about 20.7 MPag), anLHSV from about 0.2 hr⁻¹ to about 10 hr⁻¹, and a hydrogen treat gas ratefrom about 500 scf/bbl (about 85 Nm³/m³) to about 10000 scf/bbl (about1700 Nm³/m³).

During hydrotreatment, the sulfur and nitrogen contents of a feedstockcan advantageously be reduced. In an embodiment, one or morehydrotreatment stages can preferably reduce the sulfur content to asuitable level, such as about 100 wppm or less, for example about 50wppm or less, about 30 wppm or less, about 20 wppm or less, about 15wppm or less, about 10 wppm or less, about 5 wppm or less, or about 3wppm or less. Additionally or alternately, with regard to nitrogen, thehydrotreating stage(s) can preferably reduce the nitrogen content of thefeed to about 30 wppm or less, for example about 20 wppm or less, about10 wppm or less, about 5 wppm or less, or about 3 wppm or less.

Hydrotreatment can additionally or alternately be used to deoxygenate afeed. Deoxygenating a feed can avoid problems with catalyst poisoning ordeactivation due to the creation of water or carbon oxides duringhydroprocessing. Substantially deoxygenating a feed via hydrotreatmentcan correspond to removing at least 90%, for example at least 95%, atleast 97%, at least 98%, or at least 99% of the oxygen present in thebiocomponent feedstock. Alternatively, substantially deoxygenating thefeedstock can correspond to reducing the oxygenate level of the totalfeedstock to 0.5 wt % or less, for example 0.1 wt % or less, 0.05 wt %or less, 0.01 wt % or less, or 0.005 wt % or less.

If a hydrotreatment stage is used prior to a dewaxing stage, aseparation device can, in some embodiments, be used to separate outimpurities prior to passing the hydrotreated feedstock to the dewaxingstage. The separation device can be a separator, a stripper, afractionator, or other device suitable for separating gas phase productsfrom liquid phase products. For example, a separator stage can be usedto remove H₂S and NH₃, inter alia, formed during hydrotreatment.Alternately, the entire effluent from the hydrotreatment stage can becascaded to the dewaxing stage, if desired.

Catalytic dewaxing relates to the removal and/or isomerization of longchain, paraffinic molecules from feeds. Catalytic dewaxing can beaccomplished by selective hydrocracking and/or by hydroisomerizing theselong chain molecules. Hydrodewaxing catalysts can typically includemolecular sieves such as crystalline aluminosilicates (zeolites),silicoaluminophosphates (SAPOs), or the like. In an embodiment, themolecular sieve can comprise a 1-D or 3-D molecular sieve, e.g., a10-membered ring 1-D molecular sieve. Examples of suitable molecularsieves for hydrodewaxing can include, but are not limited to, ZSM-48,ZSM-23, ZSM-35, zeolite Beta, zeolite Y, USY, ZSM-5, and combinationsthereof, particularly ZSM-48 and/or ZSM-23. Optionally, the dewaxingcatalyst can include a binder for the molecular sieve, such as alumina,titania, silica, silica-alumina, zirconia, or a combination thereof,e.g., alumina and/or titania, or silica, zirconia, and/or titania.

One feature of molecular sieves that can impact the activity of themolecular sieve is the ratio of silica to alumina (Si/Al₂) in themolecular sieve. In an embodiment, the molecular sieve can have a silicato alumina ratio of about 200:1 or less, for example about 150:1 orless, about 120:1 or less, about 100:1 or less, about 90:1 or less, orabout 75:1 or less. Additionally or alternately, the molecular sieve canhave a silica to alumina ratio of at least about 30:1, for example atleast about 50:1, or at least about 65:1.

The dewaxing catalyst can typically include a metal hydrogenationcomponent, such as a Group VIII metal. Suitable Group VIII metals caninclude Pt, Pd, Ni, or the like, or a combination thereof. The dewaxingcatalyst can generally include at least about 0.1 wt % of the Group VIIImetal, for example at least about 0.3 wt %, at least about 0.5 wt %, atleast about 1.0 wt %, at least about 2.5 wt %, or at least about 5.0 wt%. Additionally or alternately, the dewaxing catalyst can include about10.0 wt % or less of the Group VIII metal, for example about 5.0 wt % orless, about 2.5 wt % or less, or about 1.5 wt % or less.

In some embodiments, the dewaxing catalyst can optionally include aGroup VIB metal, such as W and/or Mo, in addition to the Group VIIImetal. An example of such an embodiment could be a dewaxing catalystthat includes Ni and W, Ni and Mo, or Ni, Mo, and W. In such anembodiment, the dewaxing catalyst can include at least about 0.5 wt % ofthe Group VIB metal, for example at least about 1.0 wt %, at least about2.5 wt %, or at least about 5.0 wt %. Additionally or alternately insuch an embodiment, the dewaxing catalyst can include about 20.0 wt % orless of the Group VIB metal, for example about 15.0 wt % or less, about10.0 wt % or less, about 5.0 wt % or less, or about 1.0 wt % or less. Inembodiments where the Group VIII metal is present without acorresponding Group VIB metal, the Group VIII can advantageously includePt and/or Pd.

Catalytic dewaxing can be performed by exposing a feedstock to adewaxing catalyst under effective (catalytic) dewaxing conditions.Effective dewaxing conditions can include a temperature of at leastabout 500° F. (about 260° C.), for example at least about 550° F. (about288° C.), at least about 600° F. (about 316° C.), or at least about 650°F. (343° C.); additionally or alternately, the temperature can be about750° F. (about 399° C.) or less, for example about 700° F. (about 371°C.) or less, or about 650° F. (about 343° C.) or less. Effectivedewaxing conditions can additionally or alternately include a totalpressure of at least about 400 psig (about 2.8 MPag), for example atleast about 500 psig (about 3.5 MPag), at least about 750 psig (about5.2 MPag), or at least about 1000 psig (about 6.9 MPag); additionally oralternately, the pressure can be about 1500 psig (about 10.4 MPag) orless, for example about 1200 psig (about 8.3 MPag) or less, about 1000psig (about 6.9 MPag) or less, or about 800 psig (about 5.5 MPag) orless. Effective dewaxing conditions can further additionally oralternately include an LHSV of at least about 0.1 hr⁻¹, for example atleast about 0.5 hr⁻¹, at least about 1.0 hr⁻¹, or at least about 1.5hr⁻¹; additionally or alternately, the LHSV can be about 10.0 hr⁻¹ orless, for example 5.0 hr⁻¹ or less, about 3.0 hr⁻¹ or less, or about 2.0hr⁻¹ or less. Effective dewaxing conditions can still furtheradditionally or alternately include a treat gas rate can be at leastabout 500 scf/bbl (about 85 Nm³/m³), at least about 750 scf/bbl (about130 Nm³/m³), or at least about 1000 scf/bbl (about 170 Nm³/m³);additionally or alternately, the treat gas rate can be about 5000scf/bbl (about 845 Nm³/m³) or less, for example about 3000 scf/bbl(about 510 Nm³/m³) or less, about 2000 scf/bbl (about 340 Nm³/m³) orless, about 1500 scf/bbl (about 255 Nm³/m³) or less, or about 1250scf/bbl (about 210 Nm³/m³) or less.

A catalytic dewaxing process can modify a feedstock in one or more ofseveral ways. The catalytic dewaxing process can remove oxygen in thebiocomponent portion of the feedstock. Olefins in the feedstock can beat least partially saturated (i.e., hydrogenated). The dewaxing processcan improve one or more cold flow properties of the feed, such as pourpoint and/or cloud point. The dewaxing process can remove some sulfurand/or nitrogen from the feedstock. It is noted that priorhydrotreatment of a biocomponent feed can remove substantially all ofthe oxygen and can saturate olefins. As a result, a dewaxing processperformed on a previously hydrotreated feed may perform only limiteddeoxygenation and/or olefin saturation.

After catalytic hydrotreatment of a feed, or after optionalhydrotreating and/or dewaxing, the feed can optionally be hydrofinished.A hydrofinishing stage can be similar to a hydrotreating stage, thoughgenerally under somewhat milder conditions than conventionalhydrotreating, with a goal of saturating any remaining olefins and/orresidual aromatics. A post-dewaxing hydrofinishing can, in someembodiments, be carried out in cascade with the dewaxing step. Ahydrofinishing stage can typically operate at a temperature from about150° C. to about 350° C., for example from about 180° C. to about 250°C., at a total pressure from about 2.8 MPag (about 400 psig) to about20.7 MPag (about 3000 psig), at a liquid hourly space velocity fromabout 0.1 hr⁻¹ to about 5 hr⁻¹, for example from about 0.5 hr⁻¹ to about3 hr⁻¹, and at a hydrogen treat gas rate from about 43 Nm³/m³ (about 250scf/bbl) to about 1700 Nm³/m³ (about 10,000 scf/bbl).

Suitable hydrofinishing catalysts can be similar in nature tohydrotreating catalysts. Alternately, an aromatic saturation catalystcan be used in a hydrofinishing step, such as a Group VIII and/or GroupVIB metal supported on a bound support from the M41S family, e.g., boundMCM-41. Suitable M41S binders can include, but are not limited to,alumina, silica, or any other binder or combination of binders thatprovides a high productivity and/or low density catalyst. One example ofa suitable aromatic saturation catalyst is Pt and/or another metal onalumina bound mesoporous MCM-41. Such a catalyst can be made, e.g., byimpregnating mesoporous MCM-41 (optionally pre-bound) with ahydrogenation metal such as Pt, Pd, another Group VIII metal, a GroupVIB metal, or a mixture thereof. In some embodiments, the amount ofGroup VIII metal can be at least 0.1 wt %, for example at least 0.3 wt%, at least 0.5 wt %, or at least 0.6 wt %, based on catalyst weight;additionally or alternately, the amount of Group VIII metal can be 1.0wt % or less, for example 0.9 wt % or less, 0.75 wt % or less, or 0.6 wt% or less, based on catalyst weight. Additionally or alternately, theamount of metal(s), either individually or in mixtures, can be at least0.1 wt %, for example at least 0.3 wt %, at least 0.5 wt %, at least 0.6wt %, at least 0.75 wt %, or at least 1 wt %, based on catalyst weight;further additionally or alternately, the amount of metal(s), eitherindividually or in mixtures, can be 35 wt % or less, for example 25 wt %or less, 20 wt % or less, 15 wt % or less, 10 wt % or less, or 5 wt % orless, based on catalyst weight.

In one embodiment, the hydrofinishing stage can be performed in the samereactor as the hydrodewaxing, with the same treat gas and at theapproximately the same temperature. Additionally or alternately,stripping does not occur in some embodiments between the hydrofinishingand catalytic dewaxing stages.

Integration of Hydrothermal Treatment with Hydroprocessing

FIG. 3 schematically shows a reaction system for incorporating thehydrocarbon products from catalytic hydrothermal processing into ahydroprocessing reaction.

In FIG. 3, catalytic hydrothermal reactor 380 can represent a reactorand corresponding separation devices for generating separate outputstreams. Inputs to reactor 380 can include a hydrogen stream 384, analgae stream 382, and an optional water stream 385. Optionally, algaestream 382 and water stream 385 may be combined. FIG. 3 shows that heatexchanger 390 can be used to extract heat from the water effluent 389from reactor 380 for heating of input stream 385. In some embodiments,other options can be selected for heat integration. For instance, theheat from an output stream from reactor 380 can be used to heat an inputstream to reactor 380 and/or an input stream to one of thehydroprocessing stages.

Output 388 can correspond to a separated hydrocarbon fraction fromreactor 380. This separated hydrocarbon fraction can optionallyrepresent a distilled portion or cut of the hydrocarbon output ofreactor 380, such as a portion having a boiling range from about 193° C.to about 360° C. Output 388 can then be optionally combined with afeedstock 310. The combination of output 388 and feedstock 310 can beprior to entering hydrotreatment reactor 320, or the feeds can becombined in reactor 120. The optional feedstock 310 can represent amineral feed, a biocomponent feed, or a combination thereof. Note thatcombining output 388 with feedstock 310 is only one possible choice forcombining the output from catalytic hydrothermal treatment with anotherfeed. The product from a catalytic hydrothermal treatment can becombined with another feed either before additional hydroprocessing, inbetween stages of additional hydroprocessing, or after additionalhydroprocessing.

In the embodiment shown in FIG. 3, mineral and/or biocomponent feedstock310 can be introduced into first hydrotreatment reactor 320 along withthe hydrocarbon output 388 from catalytic hydrothermal treatment reactor380. A hydrogen treat gas stream 315 can also be introduced intohydrotreatment reactor 320. The combined feedstock can be exposed tohydrotreating conditions in first hydrotreatment reactor 320 in thepresence of one or more catalyst beds that contain hydrotreatingcatalyst. Depending on the nature of the combined feedstock, thehydrotreatment can reduce the sulfur content of the treated feedstock toabout 50 wppm or less, for example about 30 wppm or less, about 20 wppmor less, about 10 wppm or less, about 5 wppm or less, or about 3 wppm orless. Depending on the nature of the combined feedstock, thehydrotreatment can reduce the nitrogen content of the treated feedstockto about 20 wppm or less, for example about 10 wppm or less, about 5wppm or less, or about 3 wppm or less. The hydrotreated feedstock 318can optionally flow from hydrotreatment reactor 310 into a separationdevice 325, where gas phase products can be separated from liquid phaseproducts. The liquid output 328 from separation device 325 can then becombined with biocomponent feedstock 312.

In an alternate embodiment, hydrotreatment reactor 320 and separationdevice 325 can be omitted. In such an embodiment, the output 388 andoptional mineral and/or biocomponent feedstock 310 can pass directlyinto conduit 328. Optionally, yet another mineral and/or biocomponentfeed 312 can be added at this point.

The hydrotreated feedstock 328 can be combined with optional feedstock312 prior to entering dewaxing reactor 340. The combined feedstock canbe exposed to catalytic dewaxing conditions in the presence of one ormore catalyst beds that contain a dewaxing catalyst. The catalyticdewaxing conditions can be sufficient to substantially hydrodeoxygenatethe feed.

The effluent 348 from catalytic dewaxing can optionally be hydrofinishedin a hydrofinishing stage 360. Depending on the configuration, eithereffluent 318, effluent 328, effluent 348, or effluent 368 can beconsidered as a hydroprocessed product for further use and/orprocessing.

1. A method for hydrothermally processing biomass, comprising:contacting an algae based feed with water in the presence of catalystparticles under effective hydrothermal processing conditions to producea multi-phase product, the catalyst particles including a catalyst metaland having an average particle size of at least about 1000 μm;separating the multi-phase product to produce at least a gas phaseportion, a liquid hydrocarbon portion, an aqueous portion, and a solidsportion, the solids portion containing the catalyst particles and algaebased solids; and separating the catalyst particles from the algae basedsolids.
 2. The method of claim 1, wherein the average particle size ofthe catalyst particles is at least about 2000 μm.
 3. The method of claim1, wherein the support for the catalyst particles comprises ahydrothermally stable support material.
 4. The method of claim 1,wherein the support for the catalyst particles comprises titania,zirconia, or a combination thereof.
 5. The method of claim 1, whereinthe support for the catalyst particles includes 0.1 wt % or less ofalumina.
 6. The method of claim 1, wherein the catalyst particlesfurther comprise a hydrothermally stable binder.
 7. The method of claim1, wherein the catalyst metal comprises Co, Ni, Mo, or a combinationthereof.
 8. The method of claim 1, wherein the catalyst metal comprisesPt, Pd, Rh, Ru, Ir, or a combination thereof.
 9. The method of claim 1,wherein the catalyst metal is in the form of an oxide or a sulfide. 10.The method of claim 1, wherein the catalyst metal is in the form of acatalyst metal salt.
 11. The method of claim 1, wherein the effectivehydrothermal processing conditions include a temperature from about 150°C. to about 500° C. and a pressure from about 4.5 barg (about 450 kPag)to about 300 barg (about 30 MPag).
 12. The method of claim 1, whereinthe effective hydrothermal processing conditions include a partialpressure of reducing gas of at least about 2 bar (about 0.2 MPa),wherein the reducing gas is hydrogen.
 13. The method of claim 1, whereinthe catalyst particles are separated from the algae based solids priorto or during separation of the solids portion from the aqueous portion.14. The method of claim 1, wherein contacting the algae based feed withwater under effective hydrothermal processing conditions substantiallydoes not result in a phase change for the water.
 15. The method of claim1, wherein the algae based feed and the water are introduced into thereactor as a mixture of algae and water.
 16. The method of claim 1,wherein the weight ratio of water to algae is from about 3:1 to about5:1.
 17. The method of claim 1, wherein the catalyst particles arepresent in an amount from about 1 wt % to about 20 wt %, based on aweight of the algae.
 18. The method of claim 1, further comprisingseparating the hydrocarbon liquid product to produce a fraction havingat least 90% of its boiling range between about 193° C. and about 360°C.
 19. A method for hydrothermally processing biomass, comprising:contacting an algae based feed with water in the presence of catalystparticles under effective hydrothermal processing conditions to producea multi-phase product, the catalyst particles including a catalyst metaland having a minimum average particle dimension of at least about 1000μm; separating the multi-phase product to produce at least a gas phaseportion, a liquid hydrocarbon portion, an aqueous portion, and a solidsportion, the solids portion containing the catalyst particles and algaebased solids; and separating the catalyst particles from the algae basedsolids.